So you bought a new Mac and now want to sync your iPhone to the new computer? Well, Apple doesn’t make that easy for you. So here’s how: Close iTunes on both Macs and copy the following folders/files from your old Mac to the new one:
Now you can sync the iPhone with the new Mac and merge the data. But be sure to backup first! By the way, thank Racker Hacker for this how-to!
P.S. The official way would be to use Apple’s “Migration Assistant” to accomplish the transfer.